Air conditioning system with two-stage compression

ABSTRACT

An air conditioning system with two-stage compression to solve the problems of high cost and low energy efficiency of the existing multi-stage compressors. Provided is an air conditioning system with two-stage compression, where the air conditioning system includes a compressor, a condenser, a throttling element, and an evaporator connected in sequence; the air conditioning system further includes a pressurizing unit disposed between the compressor and the condenser, and the pressurizing unit is capable of converting natural energy into mechanical energy to pressurize refrigerant discharged from the compressor for a second time. Since the pressurizing unit is capable of converting natural energy into mechanical energy to pressurize refrigerant discharged from the compressor for a second time, the air conditioning system can utilize a driving force provided by the natural energy to achieve two-stage compression, thereby improving the energy efficiency of the two-stage compression.

FIELD

The present disclosure relates to the technical field of airconditioning, and in particular to an air conditioning system withtwo-stage compression.

BACKGROUND

As a kind of commonly used electrical appliance, air conditioners havebecome more widely used, and accordingly, requirements on theirperformances are becoming higher and higher. Taking commercial airconditioners as an example, in some special application scenarios, it isrequired to control an evaporation temperature of the air conditioningsystem to be very low. For example, the temperature in low-temperaturedevices such as large-sized cold storage or low-temperature box needs tobe controlled at −30° C. to −40° C. or even lower. In this case, asingle-stage compressor cannot meet the requirements since thecompression ratio and pressure difference are limited to a certainextent. Generally, in this situation, a solution in which a two-stagecompressor or a multi-stage compressor is used in cooperation with alow-temperature refrigerant is adopted. The refrigerant is compressedtwice by the two-stage compressor so that an evaporation temperature of−65° C. to −75° C. or even lower may be obtained.

Although the two-stage compressor or the multi-stage compressor solvesthe above problem to some extent, the following problems also inevitablyarise: firstly, the two-stage compressor is bulky and an internalstructure thereof is complicated, resulting in high manufacturing costand reduced product competitiveness; secondly, existing two-stagecompressors have a low energy efficiency during operation.

Accordingly, there is a need in the art for a new air conditioningsystem with two-stage compression to solve the above problems.

SUMMARY

In order to solve the above-mentioned problems in the related art,namely, to solve the problems of high cost and low energy efficiency ofthe existing multi-stage compressors, the present disclosure provides anair conditioning system with two-stage compression, wherein the airconditioning system includes a compressor, a condenser, a throttlingelement, and an evaporator connected in sequence; the air conditioningsystem further includes a pressurizing unit disposed between thecompressor and the condenser, and the pressurizing unit is configured tobe capable of converting natural energy into mechanical energy topressurize refrigerant discharged from the compressor for a second time.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the pressurizing unit includes a receiverand a pressurizer, the pressurizer is connected to the receiver, and thereceiver is capable of receiving the natural energy, converting thenatural energy into mechanical energy and then transmitting themechanical energy to the pressurizer so that the pressurizer pressurizesthe refrigerant for a second time.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the pressurizer is an energy accumulationpressurizer, a rotating shaft of the energy accumulation pressurizer isconnected to the receiver, a suction port of the energy accumulationpressurizer is in communication with an exhaust port of the compressor,and a discharge port of the energy accumulation pressurizer is incommunication with an intake port of the condenser.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the natural energy is marine energy, thereceiver is a hydro-turbine, and an impeller shaft of the hydro-turbineis connected to the pressurizer.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the natural energy is wind energy, thereceiver is a wind turbine, and an impeller shaft of the wind turbine isconnected to the pressurizer.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the receiver further includes a converter,and the pressurizer is connected to the receiver through the converterso that the converter transmits the mechanical energy obtained after theconversion by the receiver to the pressurizer.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the converter is a bevel-gear directionconverter, an input shaft of the bevel-gear direction converter isconnected to the receiver, and an output shaft of the bevel-geardirection converter is connected to the pressurizer.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the converter is a worm-and-gear directionconverter, an input shaft of the worm-and-gear direction converter isconnected to the receiver, and an output shaft of the worm-and-geardirection converter is connected to the pressurizer.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the air conditioning system further includesa sub-cooling unit, and the sub-cooling unit includes a sub-coolinginlet, a first sub-cooling outlet and a second sub-cooling outlet,wherein the sub-cooling inlet is in communication with a liquid outletof the condenser, the first sub-cooling outlet is in communication withan inlet of the throttling element, and the second sub-cooling outlet isin communication with the intake port of the compressor.

In a preferred technical solution of the above air conditioning systemwith two-stage compression, the air conditioning system further includesan economizer, a flasher, or a subcooler.

It can be understood by those skilled in the art that in a preferredtechnical solution of the present disclosure, the air conditioningsystem with two-stage compression includes a compressor, a condenser, athrottling element, and an evaporator connected in sequence, and ischaracterized in that the air conditioning system further includes apressurizing unit disposed between the compressor and the condenser, andthe pressurizing unit is configured to be capable of converting naturalenergy into mechanical energy to pressurize refrigerant discharged fromthe compressor for a second time.

Since the pressurizing unit is configured to be capable of convertingnatural energy into mechanical energy to pressurize refrigerantdischarged from the compressor for a second time, at the same time ofutilizing a driving force provided by the natural energy to achievetwo-stage compression, the air conditioning system with two-stagecompression of the present disclosure can also improve the energyefficiency of the two-stage compression. Specifically, when the airconditioning system is operating, the compressor firstly pressurizes therefrigerant for a first time, and after the refrigerant that has beenpressurized for the first-time is discharged from the compressor, thepressurizing unit utilizes the natural energy to provide a driving forcefor a second-time pressurizing to convert the natural energy intomechanical energy and utilize the mechanical energy to pressurize, for asecond time, the refrigerant that has been pressurized for thefirst-time. The air conditioning system of the present disclosure canachieve a second-time pressurizing without additional energyconsumption, which not only improves the performance of the airconditioning system, but also achieves zero energy consumption of thesecond-time pressurizing.

Further, by disposing a sub-cooling unit in the air conditioning system,the air conditioning system of the present disclosure can also achievesub-cooling of the refrigerant, so that at the same time of lowering theevaporation temperature, a cooling capacity and a cooling efficiency arealso improved. Specifically, by communicating a sub-cooling inlet of thesub-cooling unit with a liquid outlet of the condenser, communicating afirst sub-cooling outlet of the sub-cooling unit with an inlet of thethrottling element, and communicating a second sub-cooling outlet of thesub-cooling unit with an exhaust port of the compressor, when the airconditioning system is operating, the refrigerant discharged from theliquid outlet of the condenser is divided into two parts, wherein onepart is cooled by being evaporated into a gaseous refrigerant due tothrottling, so that the temperature of the other part is lowered andsubcooled to reduce the refrigerant temperature. The subcooled liquidrefrigerant flows out of the first sub-cooling outlet, passes throughthe throttling element and enters the evaporator for evaporation andrefrigeration, thereby achieving lower evaporation temperature andcompressor exhaust temperature; whereas the uncooled gaseous refrigerantis discharged to the exhaust port of the compressor through the secondsub-cooling outlet, and then enters the pressurizing unit with therefrigerant discharged from the compressor for a second-timepressurizing to improve the cooling capacity and cooling efficiency.

BRIEF DESCRIPTION OF DRAWINGS

The air conditioning system with two-stage compression of the presentdisclosure will be described below with reference to the accompanyingdrawings and in connection with a cooling mode. In the drawings:

FIG. 1 is a system diagram of an air conditioning system with two-stagecompression according to the present disclosure; and

FIG. 2 is a cyclic pressure-enthalpy diagram of an air conditioningsystem with two-stage compression according to the present disclosure.

LIST OF REFERENCE SIGNS

1. compressor; 11. exhaust port; 2. condenser; 21. intake port; 22.liquid outlet; 3. throttling element; 4. evaporator; 51. receiver; 52.converter; 53. pressurizer; 531. suction port; 532. discharge port; 6.sub-cooling unit; 61. sub-cooling inlet; 62. first sub-cooling outlet;63. second sub-cooling outlet.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present disclosure will bedescribed with reference to the accompanying drawings. Those skilled inthe art should understand that these embodiments are only used toexplain the technical principles of the present disclosure, and are notintended to limit the scope of protection of the present disclosure. Forexample, although the present embodiments are described in connectionwith a cooling mode, the application scenarios of the present disclosureare not limited thereto, and may be adjusted by those skilled in theart. For example, the present disclosure may also be applied to modesthat require a compressor to participate in operation, such as a heatingmode and a dehumidification mode of an air conditioning system.

It should be noted that in the description of the present disclosure,directional or positional relationships indicated by terms such as“center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”,“inner” and “outer” are based on the directions or positionalrelationships shown in the drawings. They are merely used for theconvenience of description, and do not indicate or imply that the deviceor element involved must have a specific orientation, or be configuredor operated in a specific orientation, and therefore they should not beconstrued as limiting the present disclosure. In addition, terms“first”, “second”, and “third” are only used for descriptive purposes,and should not be understood as indicating or implying relativeimportance.

In addition, it should also be noted that in the description of thepresent disclosure, terms such as “install”, “connect” and “connection”should be understood in a broad sense, unless explicitly stated anddefined otherwise; for example, they may indicate a fixed connection, adetachable connection or an integral connection, or may indicate amechanical connection or an electrical connection; or may indicate adirect connection, or an indirect connection through an intermediatemedium, or an internal communication between two elements. For thoseskilled in the art, the specific meanings of the above terms in thepresent disclosure may be interpreted according to the specificcircumstances.

First, referring to FIG. 1 and FIG. 2, an air conditioning system withtwo-stage compression according to the present disclosure will bedescribed. FIG. 1 is a system diagram of an air conditioning system withtwo-stage compression according to the present disclosure, and FIG. 2 isa cyclic pressure-enthalpy diagram of an air conditioning system withtwo-stage compression according to the present disclosure.

As shown in FIG. 1, in order to solve the problems of high cost and lowenergy efficiency of an existing multi-stage compressor 1, an airconditioning system with two-stage compression (which may be referred toas an air conditioning system hereinafter) of the present disclosuremainly includes a compressor 1, a condenser 2, a throttling element 3(such as an electronic expansion valve), and an evaporator 4 connectedin sequence, and these components constitute a conventional airconditioning circulation loop in which refrigerant is filled. Inparticular, the air conditioning system further has a pressurizing unitand a sub-cooling unit. The pressurizing unit is disposed between thecompressor 1 and the condenser 2, and the pressurizing unit isconfigured to be capable of converting natural energy into mechanicalenergy to pressurize refrigerant discharged from the compressor 1 for asecond time. The sub-cooling unit includes a sub-cooling inlet 61, afirst sub-cooling outlet 62, and a second sub-cooling outlet 63. Thesub-cooling inlet 61 is in communication with a liquid outlet 22 of thecondenser 2, the first sub-cooling outlet 62 is in communication with aninlet of the throttling element 3, and the second sub-cooling outlet 63is in communication with an exhaust port 11 of the compressor 1.

As shown in FIG. 1 and FIG. 2, when the air conditioning system isoperating, the refrigerant flowing out of the liquid outlet 22 from thecondenser 2 is divided into two parts (state point 4→5→6), wherein afirst part is cooled in a way of throttling thermal expansion under theaction of the sub-cooling unit cools, and reduces the temperature of asecond part by heat exchange. The first part of the refrigerant afterthe heat exchange comes to the exhaust port 11 of the compressor 1through the second sub-cooling outlet (state point 6→3); the second partof the refrigerant, after exchanging heat with the first part of therefrigerant, enters the evaporator 4 for evaporation after being furtherthrottled by the throttling element 3 (state point 6→7→1); therefrigerant after evaporation enters the compressor 1 for a first-timepressurizing. then is discharged through the exhaust port 11 of thecompressor 1 (state point 1→2), and is mixed with the first part of therefrigerant that comes to the exhaust port 11 of the compressor 1 (statepoint 2→3); the mixed refrigerant enters the pressurizing unit, andafter the pressurizing unit converts the natural energy into mechanicalenergy so that the mixed refrigerant is pressurized for a second time(state point 3→4), the refrigerant enters the condenser 2 again, therebycompleting one cycle.

As can be seen from the above description, since the pressurizing unitis configured to be capable of converting natural energy into mechanicalenergy to pressurize refrigerant discharged from the compressor 1 for asecond time, at the same time of utilizing the natural energy to achievetwo-stage compression, the air conditioning system with two-stagecompression of the present disclosure can also improve the energyefficiency of the two-stage compression. Specifically, when the airconditioning system is operating, the compressor 1 firstly pressurizesthe refrigerant for a first time, and after the refrigerant that hasbeen pressurized for the first-time is discharged from the compressor 1and is mixed with a part of the refrigerant from the sub-cooling unit,the pressurizing unit utilizes the natural energy to provide a drivingforce for a second-time pressurizing to convert the natural energy intomechanical energy and utilize the mechanical energy to pressurize, for asecond time, the refrigerant that has been pressurized for thefirst-time, so that the air conditioning system of the presentdisclosure can achieve a second-time pressurizing without additionalenergy consumption, which not only improves the performance of the airconditioning system, but also achieves zero energy consumption of thesecond-time pressurizing.

Further, by disposing a sub-cooling unit in the air conditioning system,the air conditioning system of the present disclosure can also achievesub-cooling of the refrigerant, so that at the same time of lowering theevaporation temperature, a cooling capacity and a cooling efficiency arealso improved. Specifically, by communicating the sub-cooling inlet 61of the sub-cooling unit with the liquid outlet 22 of the condenser 2,communicating the first sub-cooling outlet 62 of the sub-cooling unitwith the inlet of the throttling element 3, and communicating the secondsub-cooling outlet 63 of the sub-cooling unit with the exhaust port 11of the compressor 1, when the air conditioning system is operating, therefrigerant discharged from the liquid outlet 22 of the condenser 2 isdivided into two parts by the sub-cooling unit, wherein one part iscooled by being evaporated into a gaseous refrigerant due to throttling,so that the temperature of the other part is lowered and subcooled toreduce the refrigerant temperature. The subcooled liquid refrigerantflows out of the first sub-cooling outlet 62, passes through thethrottling element 3 and enters the evaporator 4 for evaporation andrefrigeration, thereby achieving lower evaporation temperature and lowerexhaust temperature of the compressor 1; whereas the uncooled gaseousrefrigerant is discharged to the exhaust port 11 of the compressor 1through the second sub-cooling outlet 63, and then enters thepressurizing unit with the refrigerant discharged from the compressor 1for a second-time pressurizing to improve the cooling capacity andcooling efficiency.

The air conditioning system with dual-stage compression according to thepresent disclosure will be described in detail below with reference toFIG. 1.

As shown in FIG. 1, in a possible embodiment, the natural energy ismarine energy, for example a source of water that can flow such asriver, stream, lake and sea. The pressurizing unit includes a receiver51, a converter 52, and a pressurizer 53. The receiver 51 is connectedto the converter 52, the converter 52 is connected to the pressurizer53, and the pressurizer 53 is disposed between the exhaust port 11 ofthe compressor 1 and the intake port 21 of the condenser 2. The receiver51 is capable of receiving an ocean energy and converting the oceanenergy into mechanical energy, and the converter 52 is capable oftransmitting the mechanical energy to the pressurizer 53, so that thepressurizer 53 utilizes the mechanical energy to pressurize therefrigerant for a second time. Specifically, the receiver 51 may be ahydro-turbine having an impeller and an impeller shaft; the converter 52may be a bevel-gear direction converter having an input shaft and anoutput shaft; and the pressurizer 53 may be an energy accumulationpressurizer having a suction port 531, a discharge port 532, a scroll,and a rotating shaft. The impeller shaft of the hydro-turbine isconnected to the input shaft of the bevel-gear direction converter, suchas by welding, key connection or coupling connection; the output shaftof the bevel-gear direction converter is connected to the rotating shaftof the energy accumulation pressurizer, such as also by welding, keyconnection or coupling connection; the suction port 531 of the energyaccumulation pressurizer is in communication with the exhaust port 11 ofthe compressor 1, and the discharge port 532 of the scroll compressor isin communication with the intake port 21 of the condenser 2. Therefore,when the water stream is flowing (such as when the seawater is at arising tide or a falling tide), the impeller of the hydro-turbine isdriven to rotate. The rotation of the impeller drives the input shaft ofthe bevel-gear direction converter to rotate, and the input shaft of thebevel-gear direction converter drives the output shaft of the bevel-geardirection converter to rotate. The output shaft further drives thescroll of the energy accumulation pressurizer to rotate. When the scrollrotates, the refrigerant is sucked in from the suction port 531 andcompressed, and is then discharged from the discharge port 532.

With continued reference to FIG. 1, in a possible embodiment, thesub-cooling unit may be an economizer, an inlet of the economizer isconnected to the liquid outlet 22 of the condenser 2, a first outlet ofthe economizer is connected to the throttling element 3, and a secondoutlet of the economizer is connected between the exhaust port 11 of thecompressor 1 and the suction port 531. When the air conditioning systemis operating, the refrigerant discharged from the liquid outlet 22 ofthe condenser 2 is divided into two parts when passing through theeconomizer, wherein one part is cooled by being evaporated into agaseous refrigerant due to throttling, so that the temperature of theother part is lowered and subcooled to reduce the refrigeranttemperature. The subcooled liquid refrigerant flows out of the firstoutlet of the economizer, passes through the throttling element 3 andenters the evaporator 4 for evaporation and refrigeration, whereas theuncooled gaseous refrigerant is discharged to the exhaust port 11 of thecompressor 1 through the second outlet of the economizer, mixes with therefrigerant discharged from the compressor 1 and then enters the energyaccumulation pressurizer together with the refrigerant for a second-timepressurizing.

In the above preferred embodiment, by converting the marine energy intomechanical energy, that is, by using the marine energy to provide adriving force for the pressurizer 53, the air conditioner of the presentdisclosure can make full use of natural resources. Especially, theresource of flowing water in a seaside city can be used to perform asecond-time pressurizing on the refrigerant. In this way, not only asignificant pressurizing effect is achieved, but also the need for anexternal power source is eliminated during the pressurizing process,thereby also greatly saving energy consumption. In addition, as comparedwith the multi-stage compressor 1, all the components of thepressurizing unit of the present disclosure are standard parts, and theassembly method is simple and reliable, so the purchase cost isrelatively reduced, and the competitiveness of the product is improved.Through the configuration of the economizer, the present disclosure canalso achieve a lower evaporation temperature and a lower exhausttemperature of the compressor 1 to improve the cooling capacity andcooling efficiency of the air conditioning system. As compared withother compressors 1, since the energy accumulation pressurizer asselected has no reciprocating mechanism therein, and the pressurizingcan be achieved merely by the rotation of the scroll, so its structureis simple, the volume is small, the weight is light, and the reliabilityis high. In addition, it has high efficiency and low noise in a range ofcooling capacity in which the present disclosure is adapted, which canimprove the user experience. The hydro-turbine and the bevel-geardirection converter not only each have a simple structure, but also havea high durability, which can improve the operating stability of the airconditioning system.

It should be noted that the above preferred embodiments are only used toexplain the principle of the present disclosure, and are not intended tolimit the scope of protection of the present disclosure. Those skilledin the art can adjust the above arrangements without departing from theprinciple of the present disclosure so that the present disclosure canbe applied to a more specific application scenario.

For example, in an alternative embodiment, there is not only onearrangement of the pressurizing unit. Those skilled in the art canadjust the arrangement of the pressurizing unit without departing fromthe principle of the present disclosure so that the present disclosurecan be applied to a more specific application scenario. For example, thepressurizing unit may not include the converter 52, but includes thereceiver 51 which is directly connected to the pressurizer 53.

As another example, in another alternative embodiment, the form of thepressurizer 53 is not invariable, as long as the pressurizer 53 isarranged such that the refrigerant can be effectively pressurized byusing the driving force provided by the natural energy without the needfor an external power supply. For example, a plunger structure may beadopted for the energy accumulation pressurizer, and the converter 52drives the plunger to reciprocate to achieve the pressurizing of therefrigerant; or the pressurizer can also be realized by modifying theexisting compressor. For example, it can be realized by modifying ascroll compressor in the following way: detaching its driving part andpower part, leaving only a scroll chamber and a scroll, and connecting arotating shaft of the scroll to an output shaft of the bevel-geardirection converter. Therefore, the purpose of using ocean energy toprovide a driving force for the scroll is achieved so that therefrigerant is pressurized for a second time. Similarly, for thereceiver 51, in addition to the hydro-turbine, any form of devicescapable of converting a marine energy into mechanical energy can beapplied to the present disclosure.

For another example, in another alternative embodiment, in addition tothe bevel-gear direction converter, a worm-and-gear direction convertermay also be used for the converter 52. In this case, the input shaft ofthe worm-and-gear direction converter is connected to the impeller shaftof the hydro-turbine, and the output shaft of the worm- and-geardirection converter is connected to the rotating shaft of the energyaccumulation pressurizer.

For still another example, in another alternative embodiment, thearrangement of the sub-cooling unit may also be adjusted. For example,the sub-cooling unit may also be a flasher, a subcooler, or the like.Alternatively, the sub-cooling unit may be omitted in the airconditioning system. All these changes do not deviate from the principleof the present disclosure, and therefore should fall within the scope ofprotection of the present disclosure.

For still another example, in another alternative embodiment, inaddition to the ocean energy, the natural energy may also be otherenergies that can be collected in nature, such as wind energy.Correspondingly, when the natural energy is wind energy, the receiver 51can be a wind turbine, and an impeller shaft of the wind turbine may bedirectly connected to the rotating shaft of the energy accumulationpressurizer or connected to the rotating shaft through the converter 52,etc., which can also achieve purpose of providing a driving force forthe pressurizer 53 without the need for an external power source so thatthe refrigerant can be pressurized for a second time.

The use of wind energy as the natural energy greatly expands theapplication scenarios of the present disclosure, so that the airconditioning system of the present disclosure can be applied to areasrich in wind energy in addition to marine energy, thereby improving thecompetitiveness of the products of the present disclosure.

Heretofore, the technical solutions of the present disclosure have beendescribed in connection with the preferred embodiments shown in thedrawings, but it can be easily understood by those skilled in the artthat the scope of protection of the present disclosure is obviously notlimited to these specific embodiments. Those skilled in the art can makeequivalent changes or replacements to the related technical featureswithout departing from the principle of the present disclosure. Thetechnical solutions after the modification or replacement will fallwithin the scope of protection of the present disclosure.

1-10. (canceled)
 11. An air conditioning system with two-stagecompression, comprising: a compressor, a condenser, a throttlingelement, and an evaporator connected in sequence; the air conditioningsystem further comprises a pressurizing unit disposed between thecompressor and the condenser, and the pressurizing unit is configured toconverting natural energy into mechanical energy to pressurizerefrigerant discharged from the compressor for a second time.
 12. Theair conditioning system with two-stage compression according to claim11, wherein the pressurizing unit comprises a receiver and apressurizer, the pressurizer is connected to the receiver, and thereceiver receives the natural energy, converts the natural energy intomechanical energy and then transmits the mechanical energy to thepressurizer so that the pressurizer pressurizes the refrigerant for asecond time.
 13. The air conditioning system with two-stage compressionaccording to claim 12, wherein the pressurizer is an energy accumulationpressurizer, a rotating shaft of the energy accumulation pressurizer isconnected to the receiver, a suction port of the energy accumulationpressurizer is in communication with an exhaust port of the compressor,and a discharge port of the energy accumulation pressurizer is incommunication with an intake port of the condenser.
 14. The airconditioning system with two-stage compression according to claim 12,wherein the natural energy is marine energy, the receiver is ahydro-turbine, and an impeller shaft of the hydro-turbine is connectedto the pressurizer.
 15. The air conditioning system with two-stagecompression according to claim 12, wherein the natural energy is windenergy, the receiver is a wind turbine, and an impeller shaft of thewind turbine is connected to the pressurizer.
 16. The air conditioningsystem with two-stage compression according to claim 12, wherein thereceiver further comprises a converter, and the pressurizer is connectedto the receiver through the converter so that the converter transmitsthe mechanical energy from the receiver to the pressurizer.
 17. The airconditioning system with two-stage compression according to claim 16,wherein the converter is a bevel-gear direction converter, an inputshaft of the bevel-gear direction converter is connected to thereceiver, and an output shaft of the bevel-gear direction converter isconnected to the pressurizer.
 18. The air conditioning system withtwo-stage compression according to claim 16, wherein the converter is aworm-and-gear direction converter, an input shaft of the worm-and-geardirection converter is connected to the receiver, and an output shaft ofthe worm-and-gear direction converter is connected to the pressurizer.19. The air conditioning system with two-stage compression according toclaim 11, wherein the air conditioning system further comprises asub-cooling unit, and the sub-cooling unit comprises a sub-coolinginlet, a first sub-cooling outlet, and a second sub-cooling outlet,wherein the sub-cooling inlet is in communication with a liquid outletof the condenser, the first sub-cooling outlet is in communication withan inlet of the throttling element, and the second sub-cooling outlet isin communication with the exhaust port of the compressor.
 20. The airconditioning system with two-stage compression according to claim 11,wherein the air conditioning system further comprises an economizer, aflasher, or a sub-cooler.